Pressure purging or dilution purging

[Student212]

Hello everyone,

I am doing a thesis to save nitrogen usage and looking for the following information.
Priority is to save N2 usage first and then time.
1. Pressure purging vs Dilution purging in terms of Time vs Volume of nitrogen required.
Theoretically from formulas i get that dilution purging is optimal but currently it takes days to complete the purging.
2.Minimum pressure of vessel for pressure purging?
3. How to measure concentration in vessel safely, is there a special equipment?( if possible bottom and top concentration)

Thank you in advance.

 

[LittleInch]

Where are you getting your information from?

Days to purge what? Didn't sound right.

Oxygen monitoring is the usual method.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Student212]

Thank you for replying.

Thats because they are doing dilution purging and stop when they wish to. They dont really check the concentration remaining etc.

1. So the problem im facing is if I do Pressure purging
Case 1: P1= Atm pressure= 1 bar
P2: Final pressure in vessel= 6 bar

Case 2 P1 = same
P2 = 11 bar

Case 2 takes more nitrogen, more time but less cycles and opposite for case 1.
How can i find a balance pressure to take such that i use less N2.

2. For Dilution purging I would like to know what should be the flow to vessel such that there is perfect mixing. Is there a formula for this.

3. What if i want to purge before maintenance to reduce chemical concentration, not oxygen. How can I know concentration at top and bottom of vessel also considering operator safety.

Thank you very much in advance.

Thank you

 

[pierreick]

Hi,
Consider the document attached.
Pierre

 

[pierreick]

Hi,
One more document to study.
Pierre

 

[waross]

Slowly fill from the bottom with CO2, vent at the top.
Then slowly fill from the top with nitrogen and vent from the bottom.

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Ohm's law
Not just a good idea;
It's the LAW!